A method has conventionally been disclosed according to which, when a user cannot assume any keyword that the user originally desires to search for, the user executes the search by inputting a partial character string of the original keyword (see, for example, Japanese Patent Nos. 3427679 and H8-194719).
However, for example, when a search is executed for “” (kekkon-katsudo: activity to marry) consisting of basic words “” (kekkon: marriage) and “” (katsudo: activity) by inputting an unregistered word such as an abbreviation thereof “” (kon-katsu) as the character string to be searched for, no search result can be acquired for “” and each of the characters needs to be searched for such as “” (kon) and “” (katsu). When each of “” and “” is found separately from each other and, as a result, “” (kekkon-seikatsu: marital life), etc., are also acquired as the search results. Therefore, a problem arises that the search precision is low.